Multivariable Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 0-53849-787-4
ISBN 13: 978-0-53849-787-9

Chapter 11 - Infinite Sequences and Series - 11.1 Exercises - Page 724: 49

Answer

converges to $ln2$

Work Step by Step

Given: $a_n=ln({2n^{2}+1})-ln({n^{2}+1})$ Use logarithm quotient rule; we have $a_n=ln(\frac{2n^{2}+1}{n^{2}+1})$ $\lim\limits_{n \to \infty}a_n=\lim\limits_{n \to \infty}ln(\frac{2n^{2}+1}{n^{2}+1})$ Divide numeartor and denominator by $n^{2}$ $=\lim\limits_{n \to \infty}ln(\frac{2+1/n^{2}}{1+1/n^{2}})$ $=ln(\frac{2+\frac{1}{\infty}}{1+\frac{1}{\infty}})$ $=ln(\frac{2+0}{1+0})$ $=ln2$ Hence, the sequence converges to $ln2$.
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